Pressure relief valve



1959 L. 1. CRUMLEY ETAL 2,917,071

PRESSURE RELIEF VALVE Filed Oct. 14, 1957 IN VEN T0125. L/oya Ma Gram/6y BY Roe r/19// Fu/fofl United States Patent 0.

PRESSURE RELIEF VALVE Application October 14, 1957, Serial No. 690,123

1 Claim. (Cl. 137-251) This invention relates to a two-way pressure relief valve designed for use in connection with a container such as a railway boxcar wherein it is desired to maintain a predetermined pressure of an inert gas or the like within the boxcar during shipment of materials that are being subjected to the gas pressure.

In the handling of alfalfa and other forage crops it is extremely important to preserve the carotene (pro-vitamin A) content or activity thereof from the time the same is initially harvested and throughout all processing and handling operations, until placed in use by the ultimate consumer. A large percentage of such crops is today placed in pellet form prior to shipment and storage and it is quite common to immediately place the pellets in storage within an inert gas such as carbon dioxide after the container has been purged of its oxygen content inasmuch as the aforementioned vitamin and carotene content is not appreciably reduced over a long perind of time as long as the air is kept therefrom.

Many of the problems incident to such operations have been met in recent years with respect to storage in stationary containers, but no satisfactory means has heretofore been provided to maintain the products within the inert gas conditions during shipment. It is proposed to transport the same by rail and it is, of course, possible to construct boxcars or the like which are substantially impervious to gas escape, but the expense is not warranted if the mobile unit is to be used only for such single purpose. Therefore, the railway companies generally preter to use existing equipment and to modify the same as inexpensively as possible to permit the hauling of the pellets while subjected to the carbon dioxide or the like.

It is the primary object of the instant invention, therefore, to provide structure that will make it possible to use present-day boxcars in the transportation of alfalfa pellets or the like while subjected to the inert gas.

Manifestly, during shipment, temperature changes result in change in the pressure of the inert gas within the boxcar and it is accordingly, the most important object of the instant invention to provide a valve that will automatically maintain the pressure of the inert gas within predetermined limits by not only exhausting the boxcar of the gas when the pressure rises beyond a certain point, but by automatically permitting flow of air into the boxcar when the pressure of the inert gas drops below a certain point.

Another important object of the present invention is to provide an automatic two-way pressure relief valve that employs two compartments interconnected by a fluid tube therebeneath to the end that in either direction of operation, the fluid is forced from the tube into one of the compartments whereby the air or gas flow is permitted by bubbling upwardly through the liquid.

Another important object of the present invention is to provide a valve of the aforementioned character that employs an elongated, horizontal tube in conjunction with a vertical U-tube therebeneath in a manner to pre- 2,917,071 Patented Dec. 15, 1959 tion of the valve so that the air or gas will properly bubble upwardly through the fluid and pass to the atmosphere, or into the boxcar as, the case may be.

Other objects include important details or construction to be made clear as the following specification progresses, reference being had to the accompanying drawing, wherein:

Fig. 1 is an end view of a pressure relief valve made pursuant to the present invention showing. the same operably mounted on a railway boxcar; and

Fig. 2 is an enlarged, cross-sectional view taken on line 11-11 of Fig. 1 showing the boxcar fragmentarily.

The pressure relief valve illustrated in the drawing includes a pair of receptacles that are presented by employment of an elongated, horizontal tube 10 of any de sired transverse configuration. The tube 10 is provided with ends 12 and 14 having ports 16 and 18 disposed above the bottom 20 of tube 10.

A vertical partition 22 in the tube 10 subdivides the same into a pair of compartments 24 and 26. A U-tube 28 provided with a bight 30 and a pair of legs 32 and 34 is connected with the tube 10 so that the legs 32 and 34 thereof communicate with compartments 24 and 26 respectively through bottom 20. Tube 28 is adapted to contain a suitable liquid 36 sufficient in quantity to completely close the same, i.e., prevent free flow of air or gas between the compartments 24 and 26 through the tube 28. A petcock 38 may be employed in leg 34 for example, to establish the liquid level in tube 28.

Identical L-shaped conduits 40 and 42 are provided at the ends 12 and 14 respectively in communication with the compartments 24 and 26 through corresponding ports 16 and 18. Each conduit 40 and 42 includes a nipple 44 connecting the tube 10 with an L 46, the latter of which is provided with a perforated cap 48 for supporting a screen wire filter 50, all for the purpose of preventing pollution of the liquid 36. The liquid 36 may be poured into the tube 28 by virtue of the provision of a plug 52 in tube 10.

An external flange 54 on the tube 10 permits attachment of the valve to one wall 56 of boxcar 58, thereby disposing the conduit 42 within the boxcar :58.

In the event the pressure differential between atmosphere and the gas contained in boxcar 58, rises beyond a predetermined limit, the gas is permitted to escape from the boxcar 58, through the conduit 42 and into the compartment 26. As the gas pressure acts upon the liquid 36, the latter is forced from the tube 28 into the compartment 24 where such liquid assumes a relatively shallow level below the port 16. Thereupon, the gas escaping from the boxcar 58 is free to bubble upwardly through the compartment 24 and thence to the atmosphere via the conduit 40.

Conversely, when the pressure differential drops below a predetermined limit, atmospheric air may enter the boxcar 58 through the valve in a reverse manner. In that instance, the air within compartment 24 acts on the liquid 36 to force the latter into compartment 26, whereupon the air bubbles upwardly through the liquid 36 in compartment 26 and flows into the boxcar 58 via conduit 42.

Having thus described the invention what is claimed as new and desired to be secured by Letters Patent is:

A two-way pressure relief valve comprising an elongated, horizontal tube having a pair of ends, each of said ends having a port formed therein above the bottom of the tube; a vertical partition at substantially the cenmunicatingwith. 5; corresponding comnartment through said bottom of the horizontal tube; a petcockron one leg.

wardly opening conduit'at'tached to each end respectively in communication with .said compartments through said ports; and. a; filter interposedrin each conduit respectively, there being an opening formed in the top of the horizontal tube and communicating with one ofisaid comparttube.

inents whereby 1 liquid 7 ay be pleiced said U-shaped References Cited in the file of this patent UNITED STATES PATENTS Collins et al. Oct. 8, 1929 FOREIGN PATENTS Great Britain Dec. 24, 1919 

